The interaction of laser with solid target material can produce plasma called laser-induced plasma. The counteracting force is generated by the expending of laser-induced plasma. That is the foundation of laser propulsion. The measurement of impulse acting on the targets is very important for the impulse imparting from laser beam to target. A new method is presented by combining pendulum with light-electric tachometer, which is adopted in the experiment for measuring the impulse coupling between laser induced plasma and aluminum target. Considering the structure of measurement equipment and the theory of fluid mechanics, the kinetic equation of the pendulum including air damping term is founded, and target impulse is obtained by using the kinetic equation and the measured pendulum angular velocity. The comparison between experimental results and theoretical results testifies that the difference of the period of the pendulum between experimental measurement and kinetic equation is less than 0.5%. The experimental operation is simple and the experimental accuracy is high.